Brenner tumor of the ovary: A comparative immunohistochemical and ultrastructural study with transitional cell carcinoma of the bladder

Because of a fancied light microscopic resemblance to transitional epitheli um (urothelium), Brenner tumor (BT) of the ovary is commonly described as a transitional cell neoplasm. An inability to detect a great deal of similar ity between the two at the ultrastructural level prompted this electron mic roscopic study comparing 3 benign Brenner tumors with normal urothelium and 6 transitional cell carcinomas (TCC) of varying histologic grade from the urinary bladder. To complement the ultrastructural observations, the immuno phenotype of 8 benign BTs was evaluated together with that of 12 TCCs of th e bladder using antibodies to thrombomodulin (TM), cytokeratin 20, cytokera tin 7, and carcinoembryonic antigen (CEA), all of which have been shown to react with TCCs of urothelial origin. At the ultrastructural level, there w as only limited evidence of a morphologic likeness between the epithelial c ells of BTs and those of the benign or neoplastic urothelium. The immunophe notype of the two tumors also differed significantly in that there was no r eactivity for TM or cytokeratin 20 in the BTs, while these markers were exp ressed in the TCCs. Both BTs and TCCs were positive for cytokeratin 7 and m ay express CEA.